1. Field of the Invention
This invention pertains to wire cutting devices and, in particular, to hand-held and hand-operable wire cutting tools. The principles of the invention may also be implemented in automatic wire cutting machinery.
2. Description of the Prior Art
Although many types of wire cutting devices are known in the art, the structural design of these tools is such that they cannot be counted on to render a round and burrless wire end after cutting. There are many cases, particularly in the field of electronics where it is important to retain the physical shape of the cut wire. Existing wire cutters squeeze and flatten the end of the wire as they cut the wire. The consequence is having to file and dress the end before, for example, it can be threaded through a circuit board. One type of cutter contains a circular cutting function on the edge of the blades, but this is of not much help since there is no way to control the wire size to be cut, thereby limiting the points of contact between the cutting edges and the wire. An important factor in obtaining round and burrless cuts is the ratio of circumferential contact to applied force. A maximum of circumferential contact is necessary for effectiveness. When a conventional pair of wire (or lead) cutters is used, circumferential contact between the wire and cutter is at two points. Therefore, the exerted force is concentrated at these two points. Hence the reason for flattening. The opposite or best condition is for effecting full circumferential contact. In this instance, the force is almost evenly distributed. One hundred percent circumferential force can never be attained nor is it necessary. Provided circumferential contact is not less than 50% when force is applied, virtually no deformation will take place and the end of the wire will be burrless. A built prototype substantiated the reliability of the apparatus and confirmed its need.
In the prior patent art, similar type tools are disclosed in U.S. Pat. Nos. 2,560,313 for a bolt cutter; U.S. Pat. No. 2,527,735 for a rivet cutter and U.S. Pat. No. 1,767,077 for a wire cutter. The closest prior art known to the inventor is disclosed in U.S. Design Pat. No. 226,548 for a cutting tool. The present invention is designed to provide a much simplified and very inexpensive alternative to this cutting tool. The present invention is also easier to sharpen and smaller and lighter in weight than the cutting tool of U.S. Pat. No. D226,548. This improves handling, accuracy and reliability, especially in electronic applications. Furthermore, it appears that the wire cutter of the present invention will also be superior in performance.
Accordingly, it is the primary object of this invention to provide a wire or lead cutter suitable for cutting wires from 1/64" to 1/8" (or longer) diameter and leaving the ends round and burrless, in which case no further attention is needed before threading the wire through holes with limited clearance.
It is a further object of this invention to provide a wire or lead cutter with easy means of inserting the wire leads in predetermined holes for cutting application. Said means include a specially designed spring and guide or limit pin which ensure perfect alignment of the countersunk holes at all time.
It is a still further object of this invention to provide a wire (or Lead) cutting device of perfectly aligned holes in increments of 1/64 of an inch, the smallest being 1/32 inch and the holes being countersunk on one side of the tool to ease threading.
It is a specific object of this invention to provide a simple and economical wire (or lead) cutting device designed to effect a clean cut free of burrs and without alterations to the roundness of the wire (or lead) end.
The wire cutting device of this invention comprises a pair of pivotally connected jaws each having an operating handle, a portion of one jaw overlapping a portion of the other, the overlapping portions being essentially a pair of flat, toolsteel blades, one of which has a guide pin which rides in a channel in the other, thus limiting the pivotal movement of the jaws. Each jaw blade has one or more holes drilled therein such that the holes of each blade coincide when the handles are in the extreme open position, the upper side of one blade having countersunk holes to permit the easy insertion of a length of wire. The holes correspond to approximate wire gauge diameters. When the handles are closed, the jaw blades cut an inserted wire at the point where it intersects the inner mating surfaces of the jaw blades. At this point the holes no longer coincide, but are displaced completely from one another. A spring in the handles together with the guide pin in its channel regulate the full open and closed position of the aligned cutting holes of the tool when the handles are squeezed or relaxed.